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Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes Using Ion Mobility-Mass Spectrometry
Published on: June 8, 2022
Metal-assisted Lossen rearrangement
Lucie Jašíková1, Eva Hanikýřová, Anton Škríba
1Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843 Prague 2, Czech Republic.
The Journal of Organic Chemistry
|February 25, 2012
Summary
This study reveals a new mechanism for the Lossen rearrangement in metal complexes of hydroxamic acids. The rearrangement involves deprotonated forms, leading to metal carbamates via N-deprotonated intermediates.
Area of Science:
- Organic Chemistry
- Reaction Mechanisms
- Coordination Chemistry
Background:
- The Lossen rearrangement is a key organic reaction for synthesizing isocyanates.
- Understanding the mechanism of Lossen rearrangement in metal complexes is crucial for synthetic applications.
Purpose of the Study:
- To elucidate a novel reaction mechanism for the Lossen rearrangement of hydroxamic acids.
- To investigate the role of deprotonation sites (O vs. N) in metal complexes during the rearrangement.
Main Methods:
- Infrared multiphoton dissociation (IRMPD) spectroscopy to characterize anionic forms.
- Computational chemistry for mechanistic insights.
- Mass-spectrometric studies and preparative experiments.
Main Results:
- Demonstrated that the Lossen rearrangement occurs within metal complexes of deprotonated hydroxamic acids.
- Identified O-deprotonation in zinc complexes and N-deprotonation in potassium complexes.
- Established that the rearrangement proceeds from N-deprotonated metal hydroxamates to form metal carbamates.
Conclusions:
- A new mechanism for the Lossen rearrangement in metal complexes has been proposed.
- The deprotonation site significantly influences the rearrangement pathway.
- The findings provide a deeper understanding of metal-mediated organic transformations.
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